What are the four regulative principles and what makes them important?

There's a difference between chanting Hare Krishna and following the process of Krishna consciousness. Anyone can chant anywhere and anytime and get spiritual benefit. At the same time, any mantra is more potent when received from a teacher and chanted as part of a self-purification process.

Any formal training requires discipline. The same way that scientific experiments and manufacturing processes often require controlled environments to achieve accurate results, when we avoid things that reinforce our material illusion, chanting the Hare Krishna mantra can more profoundly enhance our natural, spiritual consciousness.

Initiated devotees within the Krishna consciousness movement vow to chant a minimum quota of the Hare Krishna mantra each day on beads. They also take vows to avoid 1) intoxication, 2) illicit sex, 3) meat-eating, and 4) gambling. These are commonly known as the "four regulative principles."

Indulging in these things strongly reinforces our mistaken idea that our temporary, material body is the same as our self. When we follow the four regulative principles, it's easier to focus on the mantra with a peaceful mind. Chanting with greater focus can give such a sense of well being that we naturally want to avoid any activity that gets in the way of the spiritual happiness and heightened self-knowledge that comes as a result of attentive chanting. Our mind naturally gravitates toward things that bring us pleasure. The more we experience the deep, spiritual contentment of Krishna consciousness, the less we associate temporary thrills with pleasure and pleasure with happiness.

Intoxication means any mind-altering substance we ingest that could cause us to lose control of our faculties or behavior. This includes alcohol, recreational drugs, tobacco, and caffeine. We're eternal, spiritual beings. The very idea that we can find perfect, permanent happiness in the material world—a place where everything grows old and dies—is crazy. Adding other toxic things to our bodies that further alter our already skewed perception is not recommended in any yoga practice. A clear and steady mind is needed.

Illicit sex has both gross and subtle components. According to dharma—codes of behavior recommended for spiritual upliftment—sex is most appropriately engaged in between husband and wife for the purpose of having children. Sexual activity aside from that is considered illicit, since it doesn't connect the activity to any spiritual purpose. Contemplating and fantasizing about sex are also distractions from spiritual meditation, since thinking tends to lead to feeling and willing. And where there's a will, there's a way.

Meat eating includes fish and eggs. Becoming vegetarian doesn't make one more "spiritual," but the point is to only eat things that have been offered to Krishna. Such spiritualized food, prasadam, benefits whomever eats it. Cows who provide milk products that are offered to Krishna also make spiritual benefit, as do the plants from which the grains, fruits, and vegetables come.

Gambling includes not only casino-style games of chance but also lotteries and speculative business enterprises. Such activities foster a cheating mentality, of getting something for nothing, and can lead to addictive behavior and dishonesty in general.